Liquid crystal display (LCD) panels are used in various applications including portable electronic devices and fixed location units, such as laptops, video cameras, mobile phones, PDAs, game machines, medical instruments, automobile navigation systems, and industrial machines. In LCD applications, usually backlighting is needed to illuminate the panel. Typically, LCD backlighting can be used to provide higher brightness, longer lifetime and better uniformity features. There are many types of LCD backlighting sources, such as Electroluminescent Lamps (ELs), Light Emitting Diodes (LEDs), Cold Cathode Fluorescent Lamps (CCFLs), Flat Fluorescent Lamps (FFLs), External Electrode Fluorescent Lamps (EEFLs), Hot Cathode Fluorescent Lamps (HCFLs), and Carbon Nano Tubes (CNTs).
CCFL backlighting is commonly used in graphics and color displays, and is well suited for use in large and middle scale LCD panels. Moreover, the CCFL can be used as the illumination source for LCD panels, and may be composed of a phosphor coated glass cylinder with cathodes at either end. Further, with the increasing demanding in larger size of LCD panels, e.g., in LCD televisions or large-size LCD monitors, backlighting systems may operate with multiple CCFLs to provide desired illumination.
A high voltage Direct Current/Alternating Current (DC/AC) converter (known as an inverter) is usually required to drive the CCFL. Most CCFL DC/AC converters may be formed as tuned switch circuits designed to produce an output AC power with a specific voltage and frequency. For example, a typical CCFL inverter needs to output about 20˜80 kHz AC, with an operating voltage of about 400˜800V RMS (Root Mean Square). The inverter controller circuits can include voltage and/or current feedbacks, and dimming control. However, the prior art integrated circuit inverter controllers may have relatively high component count.